The present invention relates to a process of vapor growth and its vapor apparatus, whereby the crystallinity of a gallium nitride group semiconductor has been improved.
Conventionally, the vapor growth of a gallium nitride group semiconductor (Al.sub.x Ga.sub.1-x N; inclusive of x=0) thin film on a sapphire substrate using the process of metal-organic vapor phase epitaxy (hereinafter referred to as "MOVPE") has been studied.
The MOVPE is conducted by using a vapor growth apparatus as shown in FIG. 11. In the vapor growth apparatus, to a quartz reaction tube 7 a manifold 6 is connected, to which a supply system A of NH.sub.3, a supply system B of H.sub.2 and N.sub.2, a supply system C of trimethylgallium (hereinafter referred to as "TMG") of an organometallic compound gas, a supply system D of trimethylaluinum (hereinafter referred to as "TMA") of the organometallic compound gas and a supply system E of diethylzinc (hereinafter referred to a "DEZ") which is a reactant gas containing a doping element (hereinafter merely referred to as "dopant gas") are connected. Also, in the quartz reaction tube 7, a high frequency heating graphite susceptor 9 is provided, on which a sapphire substrate 10 is disposed, which is heated by a high frequency coil 8. Each reactant gas and carrier gas from each supply system are mixed in the manifold 6, and a mixed gas is led to the quartz reaction tube 7 and blown against tee sapphire substrate 10 to grow the Al.sub.x Ga.sub.1-x N thin film thereon.
Then, by changing the mixing ratio of each organometallic compound gas, the composition ratio can be changed and the thin film of I-type (Intrinsic) Al.sub.x Ga.sub.1-x N can be formed by doping zinc.